7. Project Summary/Abstract Alterations in exosome secretion and content have been linked to Alzheimer's disease (AD). These nanovesicles are abundant in circulation and are being examined as promising blood-based biomarkers of disease. Importantly, exosomes derived from AD patients and animal models have been shown to carry pathogenic cargo and can contribute to the spread of neuronal dysfunction. Our preliminary data provide striking new evidence that key features of early AD pathophysiology, such as mitochondrial dysfunction and altered cellular metabolism, can be mediated by exosomes derived from AD patients. The proposed study will test the hypothesis that circulating exosomes mediate systemic changes in cellular metabolism associated with early stages of AD and contribute to the spread of AD pathology over the long-term progression of disease. The primary goals of this proposal are: 1) to characterize total, neuron-derived, and astrocyte-derive exosomes across stages of AD and over the 3 year progression of disease using integrated omics analysis; and 2) to examine the mechanisms by which exosomes affect cellular metabolism, AD pathology, and cognitive decline using complementary in vitro, ex vivo, and in vivo approaches. The proposed study capitalizes on a unique and timely opportunity to utilize plasma samples from an ongoing NIA-funded study of participants in the Wake Forest Alzheimer' Disease Center Clinical Core. With the costs for sample collections, key clinical measures, and human bioenergetic profiling covered by existing funding, we have a valuable opportunity to advance our understanding of how exosome-mediated intercellular communication is involved in the onset and spread of AD pathophysiology. The results of this study will provide new mechanistic insights into mediators of AD pathology and could shift the focus of AD prevention and therapy to include strategies targeting the detrimental effects of exosome mediated intercellular signaling and systemic bioenergetic decline. The robust framework of this study will support future research efforts by advancing novel in vitro and in vivo experimental approaches, and by generating a comprehensive exosome repository and database linked to an ongoing longitudinal cohort study of AD.